Reduced Lactose Operon Expression in an Escherichia Coli Mutant Lacking Leucyl, Phenylalanyl-tRNA: Protein Transferase
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Authors
Freedman, Leonard P.
Issue Date
1980
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
A mutant of Escherichia coli has been isolated which
lacks leucyl, phenylalanyl-tRNA:protein transferase. The
transferase catalyzes the addition of leucine, phenylalanine,
or methionine to basic NH2-terminal residues of protein
or peptide acceptors. It is reported here that the
specific activities of the three enzymes coded for by the
lactose operon are reduced in the mutant as compared to its
parent and two spontaneous revertants, and that this reduction
is most pronounced in cells grown with glucose as the
carbon source. The results also indicate that when reduction occurs in the transferase-less mutant, percent activity
of the lac operon enzymes progressively decreases, moving
from the z gene (which codes for β -galactosidase) to the
y gene (which codes for lac permease) to the a gene ( which
codes for thiogalactoslde transacetylase). Because β-galactosidase
and thiogalactoside transacetylase have been
ruled out as potential substrates for the transferase, it
is probable that the transferase acts on some protein involved
in the overall control of transcription or translation
of the lac operon. Mechanisms attempting to interpret
the glucose and polarity effects in terms of a possible
substrate for the transferase are discussed.
Description
vi, 61 p.
Citation
Publisher
Kalamazoo College
License
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